The Islamic State (Isis) terror group has appointed a new leader for its branch in West Africa, the Nigeria-based Islamist outfit Boko Haram. Abu Musab al-Barnawi replaced Abubakar Shekau, who became the leader of Boko Haram in 2009.

In 2015, Al-Barnawi appeared in a Boko Haram video as the group's spokesperson. A few months later, Boko Haram was believed to have released a video featuring Shekau.

However, the unusual poor quality of the footage raised suspicions over its authenticity. Furthermore, the video was only shared on YouTube, rather than on Twitter accounts affiliated with Boko Haram's ally, IS.

"Al-Barnawi has recently been reaching out to ISIL after French military intervention cut Ansaru [Boko Haram's splinter] ties with Al-Qaeda in the Islamic Maghreb. Recently, Al Barnawi used a new Boko Haram Twitter account , al - Urhwa al Wutqha - but significantly he has not mentioned Shakau in the tweets at all," Otto said.

Why was Shekau replaced?

In 2015, rumours spread that Shekau had been killed or replaced as the leader has not made a verified video appeareance for the past year. The rumours could undermine the group's operation and loyalty of other cells.

Shekau is known for preferring Boko Haram's autonomy from foreign jihadist groups.

The fact that some Boko Haram members left the group to form other splinters has cast doubt over Shekau's leadership.

Boko Haram, which has renamed itself Iswap, fights against Western influence in Nigeria and aims to impose its version of Sharia law throughout occupied territories.

The group launches attacks in Nigeria and neighbouring countries in a bid to take control of more territory. Three Nigerian states − Adamawa,Borno and Yobe − have been under a state of emergency since May 2013.